Integrated electrochemical detection system

Abstract

The invention provides an integrated electrochemical detection system. The integrated electrochemical detection system comprises a power supply circuit module, a microcontroller module, a signal processing module and a three-electrode module, the signal processing module comprises a three-electrode constant potential unit, an open-circuit potential unit and an impedance measuring unit; the input end of the three-electrode constant potential unit is connected with the microcontroller module through a digital-to-analog conversion circuit, and the output end of the three-electrode constant potential unit is connected with the microcontroller module through an analog-to-digital conversion circuit; the open circuit potential unit is connected with the microcontroller module through the analog-to-digital conversion circuit; and the microcontroller module is used for controlling any one of the three-electrode constant potential unit, the open-circuit potential unit and the impedance measurement unit to work. The integrated electrochemical detection system provided by the invention has the advantages of low cost, low power consumption, portability and integration of multiple detection modes, and can be suitable for on-site rapid electrochemical detection in different scenes.

Description

Technical Field

[0001] The invention belongs to the technical field of electrochemical detection, and in particular relates to an integrated electrochemical detection system. Background Art

[0002] The electrochemical detection system, also known as the electrochemical workstation, is a measurement device specifically used for electrochemical research and teaching. It integrates a potentiostat, a galvanostat, and an electrochemical AC impedance analyzer to accurately control and measure changes in current, potential, impedance, and other related parameters in the electrochemical cell. Depending on the application scenario, various electrochemical reactions and measurements can be achieved using the built-in detection methods in the electrochemical detection system. The electrochemical detection technology has the advantages of high sensitivity, simple operation, fast analysis speed, and online detection. It is widely used in analytical sensing, environmental monitoring, food safety, and medical diagnosis.

[0003] At present, mature commercial electrochemical detection systems include the Princeton PARSTAT series in the United States, the Swiss Metrohm, the Dutch Palmsens, and the domestic Shanghai Chenhua CHI series. Although these detection systems integrate a variety of electrochemical detection methods and powerful data analysis software, they are usually large in size, expensive, and power-hungry. They are limited to laboratory analysis and cannot be used for on-site detection. Therefore, it is particularly important to develop low-cost, portable, integrated, stable and reliable electrochemical detection systems suitable for on-site rapid detection in the direction of sudden emergencies and long-term monitoring applications. Summary of the invention

[0004] In view of this, the present invention aims to propose an integrated electrochemical detection system to solve the problem that the existing electrochemical detection system has a low degree of integration and is not conducive to on-site portability and use.

[0005] To achieve the above object, the technical solution of the present invention is achieved as follows: An integrated electrochemical detection system includes a power supply circuit module, a microcontroller module, a signal processing module and a three-electrode module; A signal processing module, comprising a three-electrode constant potential unit, an open circuit potential unit and an impedance measurement unit; the input end of the three-electrode constant potential unit is connected to the microcontroller module through a digital-to-analog conversion circuit, and the output end is connected to the microcontroller module through an analog-to-digital conversion circuit; the open circuit potential unit is connected to the microcontroller module through the analog-to-digital conversion circuit; and the impedance measurement unit is connected to the microcontroller module; A three-electrode module, comprising three electrodes; wherein the three electrodes include a CE electrode, a WE electrode and a RE electrode, the three electrodes are all connected to a three-electrode constant potential unit, an open circuit potential unit is connected to the WE electrode and the RE electrode, and an impedance measurement unit is connected to the WE electrode and the RE electrode; A microcontroller module, used for receiving instructions from a host computer and controlling the operation of any one of the three-electrode constant potential unit, the open circuit potential unit and the impedance measurement unit according to the instructions from the host computer; The power supply circuit module is used to supply power to the microcontroller module, the signal processing module digital-analog conversion circuit and the analog-to-digital conversion circuit.

[0006] Furthermore, the three-electrode constant potential unit includes a voltage bias circuit, a low-pass filter circuit 1, a three-electrode constant potential circuit, a current-to-voltage circuit and a low-pass filter circuit 2; The three-electrode interfaces of the three-electrode constant potential circuit are connected to the three electrodes respectively; The input end of the voltage bias circuit is connected to the output end of the digital-to-analog conversion circuit, and the output end of the voltage bias circuit is connected to the three-electrode constant potential circuit through a low-pass filter circuit 1; The current-to-voltage circuit is used to convert and amplify the reaction current signal measured by the three-electrode constant potential circuit into a voltage signal. The two input ends of the current-to-voltage circuit are respectively connected to the three-electrode constant potential circuit and the low-pass filter circuit one, and the output end of the current-to-voltage circuit is connected to the input end of the analog-to-digital conversion circuit through the low-pass filter circuit two.

[0007] Furthermore, the three-electrode constant potential circuit includes a resistor R46, an operational amplifier U16, an operational amplifier U17 and a three-electrode interface; the output end of the low-pass filter circuit one is electrically connected to the same-direction input end of the operational amplifier U17, the WE pole of the three-electrode interface and an input end of the current-to-voltage circuit are both electrically connected to the reverse input end of the operational amplifier U17, and the output end of the operational amplifier U17 is electrically connected to the input end of the low-pass filter circuit two; the reverse input end and the output end of the operational amplifier U16 are both electrically connected to the ground, and the same-direction input end of the operational amplifier U16 is electrically connected to the RE pole of the three-electrode interface; the CE pole of the three-electrode interface is electrically connected to the ground, one end of the resistor R46 is electrically connected to the CE pole of the three-electrode interface, and the other end is electrically connected to the RE pole of the three-electrode interface.

[0008] Furthermore, the voltage bias circuit includes resistor R14, resistor R15, resistor R16, resistor R17 and operational amplifier U8.1; one end of the resistor R14 is electrically connected to the reverse input terminal of the operational amplifier U8.1, and the other end is electrically connected to a voltage output terminal of the digital-to-analog conversion circuit; one end of the resistor R16 is electrically connected to the same-direction input terminal of the operational amplifier U8.1, and the other end is electrically connected to another voltage output terminal of the digital-to-analog conversion circuit; one end of the resistor R15 is electrically connected to the output terminal of the operational amplifier U8.1, and the other end is electrically connected to the reverse input terminal of the operational amplifier U8.1; one end of the resistor R17 is electrically connected to the same-direction input terminal of the operational amplifier U8.1, and the other end is electrically connected to the ground; the output terminal of the operational amplifier U8.1 is electrically connected to the input terminal of the low-pass filter circuit.

[0009] Furthermore, the current-to-voltage circuit includes an operational amplifier U8.2, a resistor R18 and a capacitor C38, and the same-direction input terminal and the reverse input terminal of the operational amplifier U8.2 serve as two input terminals of the current-to-voltage circuit; the same-direction input terminal of the operational amplifier U8.2 is electrically connected to the output terminal of low-pass filter circuit one, and the reverse input terminal of the operational amplifier U8.2 is electrically connected to the three-electrode constant potential circuit; after the resistor R18 and the capacitor C38 are connected in parallel, one end is electrically connected to the reverse input terminal of the operational amplifier U8.2, and the other end is electrically connected to the output terminal of the operational amplifier U8.2; the output terminal of the operational amplifier U8.2 is electrically connected to the input terminal of low-pass filter circuit two.

[0010] Furthermore, the open circuit potential unit includes an open circuit potential circuit and a low-pass filter circuit three, the two input ends of the open circuit potential circuit are electrically connected to the WE electrode and the RE electrode respectively, and the output end of the open circuit potential circuit is electrically connected to the analog-to-digital conversion circuit through the low-pass filter circuit three.

[0011] Furthermore, the impedance measurement unit includes an impedance measurement circuit, a bandpass filter circuit 1 and a bandpass filter circuit 2; the impedance measurement circuit is connected to the microcontroller module, the RE electrode is electrically connected to the impedance measurement circuit through the bandpass filter circuit 1, and the WE electrode is electrically connected to the impedance measurement circuit through the bandpass filter circuit 2.

[0012] Furthermore, the microcontroller module adopts STM32F1 series products, the digital-to-analog conversion circuit adopts ADS12 series products, and the analog-to-digital conversion circuit adopts DAC85 series products.

[0013] Furthermore, the system also includes a wireless communication circuit connected to the microcontroller module.

[0014] Furthermore, the wireless communication circuit adopts a VG series Bluetooth chip.

[0015] Compared with the prior art, the integrated electrochemical detection system described in the present invention has the following advantages: (1) The integrated electrochemical detection system described in the present invention has the advantages of low cost, low power consumption, portability and integration of multiple detection modes. It can be applied to on-site rapid electrochemical detection in different scenarios. It can not only meet the economic affordability of many consumers, but also is convenient for consumers to carry and use on-site, thus meeting the needs of on-site rapid detection.

[0016] (2) The integrated electrochemical detection system described in the present invention provides a rich variety of electrochemical detection methods, integrating a constant potential instrument, open circuit potential and AC impedance detection, covering the currently commonly used cyclic voltammetry, linear sweep voltammetry, differential pulse voltammetry, square wave voltammetry, amperometric IT method, open circuit potential, and AC impedance detection methods, and can meet the qualitative and quantitative testing needs of most scientific researchers or personnel engaged in electrochemical detection technology.

[0017] (3) The integrated electrochemical detection system described in the present invention improves the conventional impedance measurement circuit by introducing a bidirectional bandpass filter circuit, thereby reducing the error interference other than the measurement frequency at the input and output ends and improving the detection accuracy. At the same time, this detection system integrates the traditional three-electrode interface with the two-electrode interface, and can complete different detection modes through the free switching of the circuit, further improving the integration of the system. In addition, this detection system shows high stability and reliability. Compared with the detection results of commercial electrochemical workstations, the response trend is consistent, the current size and peak position peak difference rate is low, and it has high use value and market application prospects.

[0018] (4) The integrated electrochemical detection system described in the present invention can establish a communication protocol with a host computer through a wireless communication module, and has the advantages of simple operation, good user interaction interface, fast transmission speed, real-time dynamic display of data, data storage and cloud sharing, etc., and can achieve instant detection and analysis. In addition, this detection system has a low power consumption requirement for the power supply voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings: Figure 1 A schematic diagram of the structure of an integrated electrochemical detection system according to an embodiment of the present invention; Figure 2 A schematic diagram of the structure of a power supply circuit module in an integrated electrochemical detection system according to an embodiment of the present invention; Figure 3A schematic diagram of the circuit structure of a three-electrode constant potential circuit in an integrated electrochemical detection system according to an embodiment of the present invention; Figure 4 A schematic diagram of the circuit structure of a bandpass filter circuit 1 in an integrated electrochemical detection system according to an embodiment of the present invention; Figure 5 A schematic diagram of the circuit structure of a voltage bias circuit in an integrated electrochemical detection system according to an embodiment of the present invention; Figure 6 A schematic diagram of the circuit structure of a current-to-voltage circuit in an integrated electrochemical detection system according to an embodiment of the present invention; Figure 7 A schematic diagram of the circuit structure of a second low-pass filter circuit in an integrated electrochemical detection system according to an embodiment of the present invention; Figure 8 A test curve diagram of an integrated electrochemical detection system according to an embodiment of the present invention when performing amperometric IT detection; Fig. 9 A test curve diagram of an integrated electrochemical detection system according to an embodiment of the present invention when performing cyclic voltammetry detection; Fig.10 A test curve diagram of an integrated electrochemical detection system according to an embodiment of the present invention when performing linear scanning detection; Fig.11 This is a test curve diagram of an integrated electrochemical detection system according to an embodiment of the present invention when performing differential pulse detection.

[0020] Description of reference numerals: 1. Power supply circuit module; 2. Signal processing module; 3. Three-electrode module; 4. Microcontroller module; 5. Wireless communication circuit; 6. Digital-to-analog conversion circuit; 7. Analog-to-digital conversion circuit; 8. Three-electrode constant potential unit; 9. Open-circuit potential unit; 10. Impedance measurement unit; 11. Voltage bias circuit; 12. Low-pass filter circuit one; 13. Three-electrode constant potential circuit; 14. Current-to-voltage circuit; 15. Low-pass filter circuit two; 16. Open-circuit potential circuit; 17. Low-pass filter circuit three; 18. Impedance measurement circuit; 19. Band-pass filter circuit one; 20. Band-pass filter circuit two; 21. Lithium battery; 22. Battery charging management circuit; 23. Chip power supply circuit. DETAILED DESCRIPTION

[0021] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0022] An integrated electrochemical detection system, such as Figures 1 to 7 As shown, it includes a power supply circuit module 1, a microcontroller module 4, a signal processing module 2 and a three-electrode module 3.

[0023] The signal processing module 2 includes a three-electrode constant potential unit 8, an open circuit potential unit 9 and an impedance measurement unit 10; the input end of the three-electrode constant potential unit 8 is connected to the microcontroller module 4 through a digital-to-analog conversion circuit 6, and the output end is connected to the microcontroller module 4 through an analog-to-digital conversion circuit 7; the open circuit potential unit 9 is connected to the microcontroller module 4 through the analog-to-digital conversion circuit 7; and the impedance measurement unit 10 is connected to the microcontroller module 4. Specifically, the digital-to-analog conversion circuit 6 is used to convert the digital signal transmitted by the microcontroller module 4 into a continuous analog signal, such as a specific output current or voltage signal. The signal processing module 2 is used to process, amplify and filter the analog signal from the digital-to-analog conversion circuit 6 or the three-electrode module 3, and provide a stable and accurate excitation signal for the three-electrode module 3, such as a constant potential and a constant current. The analog-to-digital conversion circuit 7 is used to convert the analog signals such as voltage, current and impedance of the signal processing module 2 into digital signals that can be analyzed and processed by the microcontroller module 4.

[0024] The three-electrode module 3 includes three electrodes; wherein the three electrodes include a CE electrode, a WE electrode and a RE electrode, all of which are connected to a three-electrode constant potential unit 8, an open circuit potential unit 9 is connected to the WE electrode and the RE electrode, and an impedance measurement unit 10 is connected to the WE electrode and the RE electrode.

[0025] The microcontroller module 4 is used to receive instructions from the host computer and control the operation of any one of the three-electrode constant potential unit 8, the open circuit potential unit 9 and the impedance measurement unit 10 according to the instructions from the host computer.

[0026] The power supply circuit module 1 is used to supply power to the microcontroller module 4, the digital-analog conversion circuit of the signal processing module 2, and the analog-to-digital conversion circuit 7. Exemplarily, the power supply circuit includes a lithium battery 21, a battery charging management circuit 22, and a chip power supply circuit 23. The battery charging management circuit 22 and the chip power supply circuit 23 are both connected to the lithium battery 21, wherein the chip power supply circuit 23 outputs a 5V voltage, which is respectively connected to a 3.3V voltage regulator circuit, a 2.5V voltage regulator circuit, a -3.3V negative voltage generation circuit, and a -2.5V negative voltage generation circuit. In addition, the power supply circuit also includes a Type-C (i.e., USB power supply) charging interface, which is connected to the lithium battery 21 through the battery charging management circuit 22, and the chip power supply circuit 23 can also be directly connected to the Type-C charging interface to achieve power supply.

[0027] Preferably, the three-electrode constant potential unit 8 includes a voltage bias circuit 11, a low-pass filter circuit 12, a three-electrode constant potential circuit 13, a current-to-voltage circuit 14 and a low-pass filter circuit 2 15; the three-electrode constant potential circuit 13 has three electrode interfaces connected to the three electrodes respectively; the input end of the voltage bias circuit 11 is connected to the output end of the digital-to-analog conversion circuit 6, and the output end of the voltage bias circuit 11 is connected to the three-electrode constant potential circuit 13 through the low-pass filter circuit 12; the current-to-voltage circuit 14 is used to convert and amplify the reaction current signal measured by the three-electrode constant potential circuit 13 into a voltage signal, the two input ends of the current-to-voltage circuit 14 are respectively connected to the three-electrode constant potential circuit 13 and the low-pass filter circuit 1 12, and the output end of the current-to-voltage circuit 14 is connected to the input end of the analog-to-digital conversion circuit 7 through the low-pass filter circuit 2 15.

[0028] In actual application, the three-electrode constant potential unit 8 is used to measure the electrochemical mode that requires external excitation, and the three electrodes are connected using a three-electrode interface. The open circuit potential unit 9 is used to measure the open circuit potential mode that does not require external excitation, and the WE electrode and the RE electrode are connected using a two-electrode interface. The impedance measurement unit 10 is used to perform impedance measurement, and the WE electrode and the RE electrode are connected using a two-electrode interface.

[0029] Preferably, the three-electrode constant potential circuit 13 includes a resistor R46, an operational amplifier U16, an operational amplifier U17 and a three-electrode interface; the output end of the low-pass filter circuit 12 is electrically connected to the same-direction input end of the operational amplifier U17, the WE pole of the three-electrode interface and an input end of the current-to-voltage circuit 14 are both electrically connected to the reverse input end of the operational amplifier U17, and the output end of the operational amplifier U17 is electrically connected to the input end of the low-pass filter circuit 2 15; the reverse input end and the output end of the operational amplifier U16 are both electrically connected to the ground, and the same-direction input end of the operational amplifier U16 is electrically connected to the RE pole of the three-electrode interface; the CE pole of the three-electrode interface is electrically connected to the ground, one end of the resistor R46 is electrically connected to the CE pole of the three-electrode interface, and the other end is electrically connected to the RE pole of the three-electrode interface.

[0030] In actual application, this three-electrode constant potential circuit 13 electrically connects the CE pole of the three-electrode interface to the ground, and then electrically connects the reverse input terminal and output terminal of an operational amplifier U16 to the ground, and the same-direction input terminal of the operational amplifier U16 is electrically connected to the RE pole of the three-electrode interface, which can form a voltage follower to set the RE pole to zero potential. The reverse input terminal of another operational amplifier U17 is electrically connected to the WE pole of the three-electrode interface, and then electrically connected to the current-to-voltage circuit 14, and the same-direction input terminal of the operational amplifier U17 is electrically connected to the excitation signal to form an external potential with the RE pole, thereby stimulating the electrochemical reaction.

[0031] Compared with the traditional three-electrode circuit, the three-electrode constant potential circuit 13 provided in this embodiment has a lower demand on power supply voltage and reduces circuit energy consumption, so that the detection system can use a smaller battery, improves system portability and simplifies the circuit structure. In addition, the three-electrode constant potential circuit 13 can also be used to perform electrochemical tests such as cyclic voltammetry, linear sweep voltammetry, differential pulse voltammetry, square wave voltammetry, and ampere IT, and has good versatility.

[0032] Preferably, the voltage bias circuit 11 includes a resistor R14, a resistor R15, a resistor R16, a resistor R17 and an operational amplifier U8.1; one end of the resistor R14 is electrically connected to the reverse input terminal of the operational amplifier U8.1, and the other end is electrically connected to a voltage output terminal of the digital-to-analog conversion circuit 6; one end of the resistor R16 is electrically connected to the same-direction input terminal of the operational amplifier U8.1, and the other end is electrically connected to another voltage output terminal of the digital-to-analog conversion circuit 6; one end of the resistor R15 is electrically connected to the output terminal of the operational amplifier U8.1, and the other end is electrically connected to the reverse input terminal of the operational amplifier U8.1; one end of the resistor R17 is electrically connected to the same-direction input terminal of the operational amplifier U8.1, and the other end is electrically connected to the ground; the output terminal of the operational amplifier U8.1 is electrically connected to the input terminal of the low-pass filter circuit 12.

[0033] In actual application, the voltage bias circuit 11 is used to perform a subtraction operation on the two positive voltage signals output by the digital-to-analog conversion circuit 6 and output a voltage that can be positive or negative, thereby significantly improving the detection range of the system.

[0034] The voltage bias circuit 11 provided in this embodiment realizes bipolar signal output through subtraction operation, which significantly improves the detection range and signal processing capability of the system, and at the same time enhances the flexibility and stability of the system.

[0035] Preferably, the current-to-voltage circuit 14 includes an operational amplifier U8.2, a resistor R18 and a capacitor C38, and the same-direction input terminal and the reverse input terminal of the operational amplifier U8.2 serve as the two input terminals of the current-to-voltage circuit 14; the same-direction input terminal of the operational amplifier U8.2 is electrically connected to the output terminal of the low-pass filter circuit 12, and the reverse input terminal of the operational amplifier U8.2 is electrically connected to the three-electrode constant potential circuit 13; after the resistor R18 and the capacitor C38 are connected in parallel, one end is electrically connected to the reverse input terminal of the operational amplifier U8.2, and the other end is electrically connected to the output terminal of the operational amplifier U8.2; the output terminal of the operational amplifier U8.2 is electrically connected to the input terminal of the low-pass filter circuit 2 15.

[0036] The current-to-voltage circuit 14 provided in this embodiment can improve detection accuracy by converting and amplifying a weak reaction current signal into a voltage signal that is easy to measure.

[0037] Preferably, the open circuit potential unit 9 includes an open circuit potential circuit 16 and a low-pass filter circuit 17, wherein the two input ends of the open circuit potential circuit 16 are electrically connected to the WE electrode and the RE electrode respectively, and the output end of the open circuit potential circuit 16 is electrically connected to the analog-to-digital conversion circuit 7 through the low-pass filter circuit 17. The chip model of the open circuit potential circuit 16 is selected from the AD6 series.

[0038] In actual application, the low-pass filter circuit 1 12, the low-pass filter circuit 2 15 and the low-pass filter circuit 3 17 can all adopt the same low-pass filter circuit structure and have the same function. The low-pass filter circuit can effectively reduce the error interference higher than the upper limit of the detection frequency parameter in the detection mode other than impedance detection. The low-pass filter circuit can reduce noise and interference through frequency selective filtering, smooth the signal and optimize the system performance, which significantly improves the accuracy and reliability of the detection system.

[0039] Exemplarily, taking the low-pass filter circuit 2 15 as an example, it includes an operational amplifier U8.4, a resistor R19, a resistor R20, a capacitor C39 and a capacitor C40. After the resistor R19 and the resistor R20 are connected in series, one end is electrically connected to the reverse input end of the operational amplifier U8.4, and the other end is connected to the output end of the current-to-voltage circuit 14. The output end of the operational amplifier U8.4 is electrically connected to the input end of the analog-to-digital conversion circuit 7. One end of the capacitor C39 is electrically connected to the connection between the resistor R19 and the resistor R20, and the other end is electrically connected to the output end of the operational amplifier U8.4. One end of the capacitor C40 is electrically connected to the same-direction input end of the operational amplifier U8.4, and the other end is electrically connected to the ground. Similarly, the low-pass filter circuit 12 and the low-pass filter circuit 3 17 can both adopt the same circuit structure, which will not be repeated here.

[0040] Preferably, the impedance measurement unit 10 includes an impedance measurement circuit 18, a bandpass filter circuit 19 and a bandpass filter circuit 20; the impedance measurement circuit 18 is connected to the microcontroller module 4, the RE electrode is electrically connected to the impedance measurement circuit 18 through the bandpass filter circuit 19, and the WE electrode is electrically connected to the impedance measurement circuit 18 through the bandpass filter circuit 20. The chip model of the impedance measurement circuit 18 is selected from the AD59 series.

[0041] In actual application, the bandpass filter circuit 19 and the bandpass filter circuit 20 can adopt the same bandpass filter circuit structure and have the same function. The bandpass filter circuit can allow signals within a specific frequency range to pass through, while suppressing signals of other frequencies. Specifically, the bandpass filter circuit 19 serves as the output end of the impedance measurement unit 10, and the bandpass filter circuit 20 serves as the input end of the impedance measurement unit 10, wherein the output end is the excitation voltage signal of the impedance measurement circuit 18, which is applied to the two electrodes to participate in the chemical reaction after filtering, and the input end is the reaction signal generated by the two electrodes, which is transmitted to the impedance measurement circuit 18 after filtering. In impedance measurement, this frequency selectivity can ensure that only signals related to the measurement enter the detection system, thereby avoiding interference from other frequency signals and significantly improving detection accuracy.

[0042] Exemplarily, taking the bandpass filter circuit 19 as an example, it includes an operational amplifier U12, an operational amplifier U13, a resistor R38, a resistor R39, a resistor R40, a resistor R41, a capacitor C60, a capacitor C61, a capacitor C62 and a capacitor C63. One end of the capacitor C60 is electrically connected to the output end of the impedance measurement circuit 18, and the other end is electrically connected to the output end of the operational amplifier U12 through the resistor R38. One end of the capacitor C61 is electrically connected to the connection between the capacitor C60 and the resistor R38, and the other end is electrically connected to the same-direction input end of the operational amplifier U12. One end of the resistor R39 is electrically connected to the same-direction input end of the operational amplifier U12, and the other end is electrically connected to the ground. After the resistor R40 and the resistor R41 are connected in series, one end is electrically connected to the same-direction input end of the operational amplifier U13, and the other end is electrically connected to the output end of the operational amplifier U12. One end of the capacitor C63 is electrically connected to the connection between the resistor R40 and the resistor R41, and the other end is electrically connected to the output end of the operational amplifier U13. One end of capacitor C62 is electrically connected to the same-direction input end of operational amplifier U13, and the other end is electrically connected to ground. The reverse input end of operational amplifier U13 is electrically connected to its output end, and the output end of operational amplifier U13 is also electrically connected to the RE electrode in the three-electrode interface.

[0043] Similarly, the bandpass filter circuit 20 and the bandpass filter circuit 1 19 can adopt the same circuit structure. The difference is that the corresponding capacitor C60 in the bandpass filter circuit 20 needs to be electrically connected to the WE electrode in the three-electrode interface, and the output end of the corresponding operational amplifier U13 needs to be electrically connected to the input end of the impedance measurement circuit 18, which will not be repeated here.

[0044] Optionally, the models of the operational amplifier U16, operational amplifier U17, operational amplifier U8.1, operational amplifier U8.2, operational amplifier U8.4, operational amplifier U12 and operational amplifier U13 can all adopt OPAx192 series products, which is conducive to reducing costs and achieving integration.

[0045] Preferably, the microcontroller module 4 adopts STM32F1 series products, the digital-to-analog conversion circuit 6 adopts ADS12 series products, and the analog-to-digital conversion circuit 7 adopts DAC85 series products.

[0046] In actual application, the microcontroller is the core component of the electrochemical detection system, which is responsible for controlling, processing data and coordinating the work of various components. The model is STM32F103, the mainstream enhanced ARM Cortex-M3 core, providing 72MHz main frequency, 128KB Flash and rich peripheral interfaces. Among them, the model used in the analog-to-digital conversion circuit 7 is the high-precision 24-bit ADS1220, which is compatible with SPI, convenient for communicating with the microcontroller, and the programmable data rate is up to 2000 times / second, which can meet different sampling requirements. Secondly, the digital-to-analog conversion circuit 6 uses a 16-bit, dual-channel DAC8552, which has low power consumption and allows rail-to-rail output swing within the power supply range of 2.7V to 5.5V, which can make full use of the power supply voltage range and output a wider range of analog voltages.

[0047] Preferably, the system further comprises a wireless communication circuit 5 connected to the microcontroller module 4. Exemplarily, the wireless communication circuit 5 uses a VG series Bluetooth chip. Compared with other wireless communication circuits 5, the VG series Bluetooth chip has a low-cost serial port, a small footprint, and a lower cost.

[0048] In actual application, the wireless communication circuit 5 adopts a Bluetooth circuit, and the selected model is the low-power VG6328A, which integrates a BLE communication module and has stable wireless connection performance. It can effectively reduce packet loss and error rate during data transmission and ensure the reliability of communication.

[0049] Preferably, the model of the 3.3V voltage regulator circuit is selected from AMS1117-3.3, which converts 5V to 3.3V to provide stable power for some chips; the model of the 2.5V voltage regulator circuit is selected from ME6211C25, which stabilizes 3.3V to 2.5V to ensure the power supply stability of the analog-to-digital conversion circuit; the model of the -3.3V and -2.5V negative voltage generation circuit is selected from ICL7660, which converts 3.3V to -3.3V and 2.5V to -2.5V respectively, to meet the dual power supply requirements of the operational amplifier and the analog-to-digital conversion circuit and expand the detection voltage range. In addition, the model of the battery charging management circuit is selected from SLM6880, which can be designed for two lithium batteries and has a comprehensive overvoltage and overcurrent protection mechanism to ensure the safety and reliability of the charging process.

[0050] Optionally, the detection system further includes a housing. According to the above structural description, by integrating the above modules on a circuit board and encapsulating the circuit board in the housing, a complete electrochemical detection system can be made, which has the advantages of portability, low cost, low power consumption, and high environmental adaptability. At the same time, the detection system also has the advantages of high stability and sensitivity, and has a rich voltage, current, and impedance detection modes, and a higher degree of integration.

[0051] This detection system can be operated according to the following detection process: (1) Initialization: After the electrochemical detection system is powered on, the microcontroller module sends configuration commands to the Bluetooth circuit, digital-to-analog conversion circuit, signal processing module, and analog-to-digital conversion circuit to complete the initial configuration before formal operation.

[0052] (2) Establishing communication: The host computer establishes a connection with the Bluetooth circuit through the Bluetooth communication protocol to complete pairing.

[0053] (3) Execute instructions: After the Bluetooth circuit receives the instructions sent by the host computer, it sends the instruction information to the microcontroller module through the asynchronous serial port. After being parsed by the microcontroller module, according to the selected electrochemical detection mode, a specific analog excitation signal is output to the analog front end through the analog-to-digital conversion circuit and acts on the electrode interface. Specifically, for the constant potential detection mode, the excitation signal acts on the working electrode after the potential is adjusted by the voltage bias circuit; the potential difference generated between the working electrode and the reference electrode and the current signal between the working electrode and the counter electrode are removed by the filter circuit, and then the potential of the working electrode is maintained stable by the three-electrode constant potential circuit. For open circuit potential measurement, the open circuit potential between the electrodes is obtained through the open circuit potential circuit. For impedance measurement, the impedance response at different frequencies is measured using an impedance circuit.

[0054] (4) Signal acquisition: The analog signal processed by the signal processing module is output to the analog-to-digital conversion circuit. The analog-to-digital conversion circuit samples the analog signal output by the signal processing module according to the set sampling frequency and resolution and converts it into a digital signal, and then transmits the digital signal to the microcontroller module.

[0055] (5) Data processing: The microcontroller module pre-processes the digital signal transmitted by the analog-to-digital conversion circuit, including removing outliers and smoothing. According to different electrochemical detection methods, key characteristic parameters are extracted from the pre-processed data.

[0056] (6) Data transmission: The microcontroller module encapsulates the processed test result data according to a specific communication protocol and sends it to the host computer (such as a smartphone, tablet or computer) through the Bluetooth circuit. The host computer can receive and display the test results in real time.

[0057] (7) System reset: After the test is completed, the system can be reset to restore each module to its initial state and prepare for the next test.

[0058] The integrated electrochemical detection system provided in this embodiment also has a variety of electrochemical detection modes, which can realize detection modes including ampere current-time method, cyclic voltammetry, linear sweep voltammetry, differential pulse voltammetry, square wave voltammetry, open circuit potential, AC impedance and the like.

[0059] Ampere current-time method: In a three-electrode system, a constant voltage is applied to the working electrode to cause the electroactive substances in the solution to undergo oxidation or reduction reactions on the electrode surface, and the changes in current and time are recorded. Figure 8 The response current of the electrochemical detection system provided in this embodiment is close to the test result of the commercial Chenhua CHI660E.

[0060] Cyclic voltammetry: In a three-electrode system, the potential on the working electrode changes back and forth within a certain range at a set rate, forming a symmetrical triangular wave signal, which in turn drives the redox reaction at the electrode interface and records the curve of current versus potential change. Fig. 9 The electrochemical detection system provided in this embodiment is consistent with the detection trend of the commercial Chenhua CHI660E, indicating that the electrochemical detection system provided in this embodiment has high detection reliability.

[0061] Linear sweep voltammetry: In a three-electrode system, an electrode potential that changes linearly with time is applied between the working electrode and the reference electrode to obtain a voltammetric relationship curve between the electrode current and the electrode potential. Fig.10 The electrochemical detection system provided in this embodiment has a lower peak potential difference rate with the commercial Chenhua CHI660E.

[0062] Differential pulse voltammetry: In a three-electrode system, a series of positive and reverse pulse signals are superimposed on the basis of step linear scanning as excitation signals to obtain the curve of current difference and potential within the cycle. Fig.11 The electrochemical detection system provided in this embodiment has a lower peak potential difference rate with the commercial Chenhua CHI660E.

[0063] It can be seen from the above that the electrochemical detection system of the present invention has good detection reliability.

[0064] In addition, compared with existing technologies, this integrated electrochemical detection system has the following advantages: (1) This embodiment provides an integrated electrochemical detection system with the advantage of low cost. The production cost of a single set of hardware is less than 200 yuan. Compared with the currently expensive commercial electrochemical detection system, it can meet the economic affordability of many consumers. In addition, this system is highly integrated, including the integration of all functional mode corresponding chips and measurement circuits, the integration of three-electrode and two-electrode interfaces, the integration of Type-C (i.e., USB power supply) charging interface and detection system, and the digital-to-analog conversion and analog-to-digital conversion chips in the impedance measurement circuit, which reduces the use of external circuits and corresponding chips, making the length, width and thickness of the system core hardware size within the range of 6.4*4.2*1cm. Therefore, the smaller size allows the development of miniaturized and portable equipment to meet the needs of rapid on-site detection.

[0065] (2) The integrated electrochemical detection system described in this embodiment provides a rich variety of electrochemical detection methods, integrating a constant potential instrument, open circuit potential and AC impedance detection, covering the currently commonly used cyclic voltammetry, linear sweep voltammetry, differential pulse voltammetry, square wave voltammetry, amperometric IT method, open circuit potential, AC impedance and other detection methods, which can meet the qualitative and quantitative testing needs of most scientific researchers or personnel engaged in electrochemical detection technology.

[0066] (3) The integrated electrochemical detection system described in this embodiment improves the conventional impedance measurement circuit by introducing a bidirectional bandpass filter circuit, thereby reducing the error interference other than the measurement frequency at the input and output ends and improving the detection accuracy. This detection system integrates the traditional three-electrode interface with the two-electrode interface. Through the free switching of the circuit, different detection modes can be completed, further improving the integration of the system. In addition, this detection system has a low power consumption requirement for the power supply voltage, and 5V can meet the detection. In addition, it supports USB power supply and provides multiple power supply modes.

[0067] (4) The integrated electrochemical detection system described in this embodiment can establish a communication protocol with a host computer (including a smart phone, tablet or computer) through a wireless communication module, and has the advantages of simple operation, good user interaction interface, fast transmission speed, real-time dynamic display of data, data storage and cloud sharing, and can achieve instant detection and analysis. In addition, this detection system shows high stability and reliability. Compared with the detection results of existing commercial electrochemical workstations, the response trend is consistent, the current size and peak position peak difference rate is low, and it has high use value and market application prospects.

[0068] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. An integrated electrochemical detection system, characterized in that: It includes a power supply circuit module, a microcontroller module, a signal processing module and a three-electrode module; A signal processing module, comprising a three-electrode constant potential unit, an open circuit potential unit and an impedance measurement unit; the input end of the three-electrode constant potential unit is connected to the microcontroller module through a digital-to-analog conversion circuit, and the output end is connected to the microcontroller module through an analog-to-digital conversion circuit; the open circuit potential unit is connected to the microcontroller module through the analog-to-digital conversion circuit; and the impedance measurement unit is connected to the microcontroller module; A three-electrode module, comprising three electrodes; wherein the three electrodes include a CE electrode, a WE electrode and a RE electrode, the three electrodes are all connected to a three-electrode constant potential unit, an open circuit potential unit is connected to the WE electrode and the RE electrode, and an impedance measurement unit is connected to the WE electrode and the RE electrode; A microcontroller module, used for receiving instructions from a host computer and controlling the operation of any one of the three-electrode constant potential unit, the open circuit potential unit and the impedance measurement unit according to the instructions from the host computer; The power supply circuit module is used to supply power to the microcontroller module, the signal processing module digital-analog conversion circuit and the analog-to-digital conversion circuit.

2. An integrated electrochemical detection system according to claim 1, characterized in that: The three-electrode constant potential unit includes a voltage bias circuit, a low-pass filter circuit 1, a three-electrode constant potential circuit, a current-to-voltage circuit and a low-pass filter circuit 2; The three-electrode interfaces of the three-electrode constant potential circuit are connected to the three electrodes respectively; The input end of the voltage bias circuit is connected to the output end of the digital-to-analog conversion circuit, and the output end of the voltage bias circuit is connected to the three-electrode constant potential circuit through a low-pass filter circuit 1; The current-to-voltage circuit is used to convert and amplify the reaction current signal measured by the three-electrode constant potential circuit into a voltage signal. The two input ends of the current-to-voltage circuit are respectively connected to the three-electrode constant potential circuit and the low-pass filter circuit one, and the output end of the current-to-voltage circuit is connected to the input end of the analog-to-digital conversion circuit through the low-pass filter circuit two.

3. An integrated electrochemical detection system according to claim 2, characterized in that: The three-electrode constant potential circuit includes a resistor R46, an operational amplifier U16, an operational amplifier U17 and a three-electrode interface; the output end of the low-pass filter circuit one is electrically connected to the same-direction input end of the operational amplifier U17, the WE pole of the three-electrode interface and an input end of the current-to-voltage circuit are both electrically connected to the reverse input end of the operational amplifier U17, and the output end of the operational amplifier U17 is electrically connected to the input end of the low-pass filter circuit two; the reverse input end and the output end of the operational amplifier U16 are both electrically connected to the ground, and the same-direction input end of the operational amplifier U16 is electrically connected to the RE pole of the three-electrode interface; the CE pole of the three-electrode interface is electrically connected to the ground, one end of the resistor R46 is electrically connected to the CE pole of the three-electrode interface, and the other end is electrically connected to the RE pole of the three-electrode interface.

4. An integrated electrochemical detection system according to claim 3, characterized in that: The voltage bias circuit includes resistor R14, resistor R15, resistor R16, resistor R17 and operational amplifier U8.1; one end of the resistor R14 is electrically connected to the reverse input terminal of the operational amplifier U8.1, and the other end is electrically connected to a voltage output terminal of the digital-to-analog conversion circuit; one end of the resistor R16 is electrically connected to the same-direction input terminal of the operational amplifier U8.1, and the other end is electrically connected to another voltage output terminal of the digital-to-analog conversion circuit; one end of the resistor R15 is electrically connected to the output terminal of the operational amplifier U8.1, and the other end is electrically connected to the reverse input terminal of the operational amplifier U8.1; one end of the resistor R17 is electrically connected to the same-direction input terminal of the operational amplifier U8.1, and the other end is electrically connected to the ground; the output terminal of the operational amplifier U8.1 is electrically connected to the input terminal of the low-pass filter circuit.

5. An integrated electrochemical detection system according to claim 3 or 4, characterized in that: The current-to-voltage circuit includes an operational amplifier U8.2, a resistor R18 and a capacitor C38, wherein the same-direction input terminal and the reverse input terminal of the operational amplifier U8.2 serve as the two input terminals of the current-to-voltage circuit; the same-direction input terminal of the operational amplifier U8.2 is electrically connected to the output terminal of the low-pass filter circuit one, and the reverse input terminal of the operational amplifier U8.2 is electrically connected to the three-electrode constant potential circuit; after the resistor R18 and the capacitor C38 are connected in parallel, one end is electrically connected to the reverse input terminal of the operational amplifier U8.2, and the other end is electrically connected to the output terminal of the operational amplifier U8.2; the output terminal of the operational amplifier U8.2 is electrically connected to the input terminal of the low-pass filter circuit two.

6. The integrated electrochemical detection system according to claim 1, characterized in that: The open circuit potential unit includes an open circuit potential circuit and a low-pass filter circuit three, the two input ends of the open circuit potential circuit are electrically connected to the WE electrode and the RE electrode respectively, and the output end of the open circuit potential circuit is electrically connected to the analog-to-digital conversion circuit through the low-pass filter circuit three.

7. The integrated electrochemical detection system according to claim 1, characterized in that: The impedance measurement unit includes an impedance measurement circuit, a bandpass filter circuit 1 and a bandpass filter circuit 2; the impedance measurement circuit is connected to a microcontroller module, the RE electrode is electrically connected to the impedance measurement circuit through the bandpass filter circuit 1, and the WE electrode is electrically connected to the impedance measurement circuit through the bandpass filter circuit 2.

8. The integrated electrochemical detection system according to claim 1, characterized in that: The microcontroller module adopts STM32F1 series products, the digital-to-analog conversion circuit adopts ADS12 series products, and the analog-to-digital conversion circuit adopts DAC85 series products.

9. The integrated electrochemical detection system according to claim 1, characterized in that: The system also includes a wireless communication circuit connected to the microcontroller module.

10. An integrated electrochemical detection system according to claim 9, characterized in that: The wireless communication circuit adopts VG series Bluetooth chip.

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